Gaster's Visit
by TeddyBearTy
Summary: Gaster heads to Toriel's house, thinking that it'll just be them - as two adults - talking for a few hours over tea. But the goat lady has other plans. And it involves diapers... Contains forced ageplay and ABDL!
1. Prologue: The Beginning of the Diapers

**Another Undertale ABDL story for you folks!**

 **But, this one will not have Sans in it.**

 ***gasps dramatically***

 **I know, I know, everybody loves Sans and all of my stories (whether ABDL or not) should have him in it. But there are many other characters that I want to make little babies- I mean do stories for that may or may not include diapers and ageplay and cute snuggling!**

 **Nonetheless, I hope you all enjoy this!**

 **I take no ownership to UNDERTALE! It belongs to its wonderful creator Toby Fox!**

Toriel hummed to herself as she rolled the dough for the chocolate chip cookies she was making.

She was getting the house prepared for a special guest. And since her husband wasn't home since he had royal business to attend to for the week, she had to handle everything on her own. But that was something she didn't mind doing.

The goat smiled to herself as she stared down at the neatly flattened dough. She patted it a little for good measure before grabbing several shaped cookie cutters. They all varied from squares to circles along with hearts and stars.

Tori continued to hum as she quickly used the cutters to shape the cookies and afterwards placing them on a tray. Then she placed them in the already heated oven to bake. The queen smiled and stared to clean up.

While she threw things away and cleaned off the counter top, a few taps from the front door grazed her hearing.

"Coming!" she chimed, quickly washing her hands before rushing to her door. She then opened it to see Gaster, neatly dressed in his long black coat.

"Good afternoon your Majesty." he greeted, bowing slightly before getting back up again.

The lady in front of him cringed. "No, no. Toriel is fine." she then stepped aside, leaving room for anyone to enter. "Would you like to come in?"

"Certainly." the skeleton went inside just before Tori closed the door. He then turned to her, confusion on his face. "May I ask why you told me to come here?"

The goat smiled as she waved her hands. "It's nothing special. Just some bonding time with you is all. We just...barely know one another."

The scientist nodded in agreement before she rushed out of the room.

"I'll be back in a moment!"

He nodded before walking out of the foyer and into the living room. However, something looked off about this particular area.

A few items laid sprawled out on the floor including rattles, stuffed animals, building blocks and a toy train. Below these items had a playing mat that had been rolled onto the ground. It was baby blue in color with a rubber ducky pattern on it.

The weird thing about this was that these objects - that are used by babies, mind you - were way too _big_ for infant hands.

"What in the-"

"I'm back~!" the goat woman chimed before the scientist could even get the words out. She then noticed Gaster staring at the playing mat and frowned. "What's wrong doctor?"

"It's...it's nothing." he then turned to her and was shocked to see that she was carrying a large baby bag over her shoulder. It matched the mat in both color and pattern. Gaster then asked the question that had been in his mind for a while. "Do you and Asgore have a baby or...?"

Toriel blushed as her red eyes widened. She then chuckled. "No no no Gasty sweetheart! We would _never_ have children this early in our marriage. Why, we've only been like this for three years!"

"Alright...? Then-" he then blushed and quickly asked. "Wait! Did you just call me Gasty?"

"That isn't important right now." Toriel stated, throwing the question she was just given aside. "Look at yourself!"

The skeleton did just that.

He didn't see anything wrong. His outfit wasn't dirty or wrinkled and his shoes were muddy or ripped. He looked perfectly fine. And so, he looked back at the goat in confusion.

However, not before being shoved into the direction of the bathroom.

"H-Hey!" he shouted. "What are you doing?!"

"You cannot be running around dressed like that! You'll get dirty!" the queen answered.

They had then reached their destination, which was right down the hall. As she pushed Gaster inside, Toriel handed him the baby bag. She then told him.

"Get changed or no cookies for you young man!"

Gaster sighed as he took one look into the bag and cringed. Before he could retort about how childish it would make him look, the goat had already shut the door and walked back into the direction of the living room.

* * *

"T-Toriel..."

The mentioned lady turned from her reading to meet the nervous eyes of the scientist. The only thing that was visible of Gaster what his forehead, eyes and his bony fingers. The rest of his body was hidden by the wall by the entryway.

"Hi Gasty." she waved before knowing his timid state. "What's wrong sweetie?"

"This outfit makes me look childish!" he exclaimed bitterly, clutching onto the door frame as tight as he possibly could. "May I put my regular clothes back on?"

"Let me see you wearing it." she stated.

"It's humiliating..."

"Let me see..."

The scientist blushed deeply and sighed as he walked out of hiding to show off his new clothes.

He was wearing a purple onesie with matching booties. Underneath his clothing, you could see the bulge of a white diaper. On the front of his outfit also had a white pin that had a lavender and white bunny pacifier attached to it.

Toriel squealed as she got up and looked at the baby dressed skeleton before squealing like a girl would over Justin Beiber.

"You look absolutely adorable sweetie~!" she cooed, practically skipping over to him. "Oh! I can just EAT you up~!"

Gaster frowned as he looked at the queen. "This is great and all your Highness, but I rather have my clothes back on. May I?"

The goat took the diaper bag that had the scientist's clothes in it before saying. "No can do cutie pie~!" she cooed. "Not until my husband comes back from his business trip."

"Won't that'll be...?"

"In a week!" she squealed, hugging Gaster. "Oh! We are gonna have so much fun together!"

Before he could say another word, the ringing of a timer was heard along with the sweet aroma of the baked treats she had been preparing earlier. Gaster's mouth couldn't help but water as the goat woman chimed.

"Cookies are done~!"

 **Chapter 2 will be coming soon!**

 ***cackles manically while caressing a cat***

 **Let the ageplay begin...!**


	2. Day 1: Disobedience and Drugs

**Hey guys! I'm back with chapter 2!**

 **Sadly, this has nothing to do with Easter but I hope you like it anyway.**

 **I do NOT own UNDERTALE or the characters in it. They all belong to Toby Fox!**

Gaster couldn't have felt any weirder.

It was bad enough that he had to settle with walking around in a diaper and onesie. That was humiliating enough (which made him grateful that the king or any one else that he knew wasn't there). But that was just the very tip of the iceberg.

Throughout the rest of the day, Toriel had done lots of things with him. She played childish games with him such as Peekaboo and Pattycake, in which she had gave him cookies every time he did the motions right or smiled when the goat would reveal her hiding spot. She had also tried to feed him some mushed carrots in a highchair. However, the scientist refused to eat it.

She understand this and simply put the skeleton in some footie PJs before placing him to bed (in a crib) with a bottle of milk. Gaster didn't drink it and let it get cold as he felt to sleep.

The next day, the scientist opened his eyes to see the queen glaring down at him.

He blinked. "Good morning Toriel...?"

"Mommy." she corrected as she lifted the full bottle from his crib and showed it to him. "Now, explain this to me sweetheart."

Gaster looked from the beverage to the goat before stating. "That's a baby bottle."

"Why is it still full?"

"I didn't want it."

She crossed her arms as she dropped the cold container back in the crib and lifted a new one up for him to see. "That is no excuse young man. You shouldn't try to starve yourself." she then put the new bottle in the skeleton's hands. "Drink this."

He looked down at the bottle and shook it in his hand. He noticed that unlike the liquid from his previous bottle, this one was brown in color.

Chocolate milk.

He sighed as he once again looked at the goat, who still looked mad, before turning back to his drink.

His first instinct was to ripped the nipple off. But then he remembered that Toriel was still standing there. She would probably be even more mad. He looked into the goat's caring but firm red eyes before making a decision.

To make as less embarrassing as possible, he quickly drain the bottle's contents. Before the queen could even bother scolding him, the milk was already gone. Gaster burped and smiled in satisfaction at the empty bottle.

His grin turned the other way around as he let out a hiccup.

And another.

And another.

"Gasty!" Tori shrieked as she picked up the skeleton and rubbed his back. "Don't do that!"

He didn't say a word as he continued to hiccup. The queen bounced him a bit and rubbed his back.

"Hold your breath sweetie." she stated and he did just that.

But as he followed Toriel's orders, he tasted something weird on the tip of his tongue. He had no clue what it was but it didn't taste good. It was then that a thought came to him.

"Did you drug my milk?!"

The goat's crimson irises widened as she looked at the scientist. She blinked. "Now, why in the world would you think that? I wouldn't dream of it."

Gaster didn't believe her. "Yeah right. I don't think your telling the truth."

"That isn't important honey." she said simply, putting that matter away. "What do you want to do today?"

He pouted. "Stay in here."

Toriel frowned. "Where did these attitude come from Gaster?" she walked him over to the changing table. "I don't like it."

The scientist grumbled as she placed him down on the table. She had then turned him around so that his back faced her. Quickly, she zipped the footie down and Gaster blushed as the cold air touched his back.

"Dry I see." the queen commented as she looked at her boy's clean white diaper. She then happily chimed. "Not for long~!"

As his clothes were being changed, the scientist couldn't help but think over what the queen just said. By the sound of it, she probably did drug his milk but he still wasn't quite sure.

Maybe she was talking about regular urine. Y'know the kind that didn't happen when people drug your food.

While he thought things through, the goat had pulled out a purple shirt with matching socks. She then walked over to the crib and began looking for the boy's bunny pacifier.

"Now where is it?" she asked herself quietly as she moved the blanket around.

Gaster noticed this and turned to the door.

He could just try to escape...but what if he got caught? Then she would tell Asgore and he'll get fired for sure. Plus, he had no clue where his actual clothes were so leaving the place with baby stuff on was going to make him the laughing stock of the Underground.

But if he didn't get caught...the same fate would fall upon him anyway.

He took a breath as Toriel called from his crib.

"Gasty sweetie. Give Mommy a hand here. I'm trying to find your binky."

He sighed as he jumped off the changing table only to fall face first to the floor.

"Gasty!" she shrieked as she rushed over to the fallen skeleton and looked him over. "Are you okay?"

He seethed as she inspected him. He got to admit that after all of these years, this fall in particular really, really hurt. Tears were threatening to fall out of his eyes but he held them back and glared at the goat. He then asked harshly.

"What did you do to me?!"

Toriel was unfazed by the scientist's tone as she replied simply. "Nothing really. I just put a muscle relaxant and a laxative into your drink. No big deal."

Gaster's pupils shrank. "Laxative?"

She patted his head before lifting him up. "Don't worry sweetie. It isn't gonna kick in for another couple of hours." She then placed him back on the table and put his shirt and socks on. "In the meantime, let's go downstairs and play shall we?"


	3. Day 2: To Get to a Bathroom

**WARNING: This chapter contains diaper usage. But knowing that this is an ABDL story, this was suppose to be expected.**

 **I take no ownership to UNDERTALE. I'm just a huge fan. All of the characters belongs to its rightful owner, which is Toby Fox.**

"Gasty~! Look at the bunny~!"

Toriel frowned when Gaster refused to look at the the stuffed bunny that she brought out for him.

Ever since the goat had admitted to drugging the scientist's milk, he had not done anything fun with her. She tried to play Pattycake and Peekaboo with him again, only to get rejected of any attention. She tried to give him lunch, which was a slice of pumpkin pie, but he didn't eat a single bite. She had even left the room for a bit to see how he'll react only for the skeleton to not even care.

He was lucky that she was a tolerable individual.

"What's wrong?" she asked in defeat and annoyance. Even though she already knew the answer, she just wanted to hear him talk to her.

But yet and still, Gaster refused to reply.

The queen sighed as she tried to think of something that would get him out of his dreary mood. She then snapped her fingers and smiled as an idea came to mind.

"Hey Gasty~?" she chimed, dashing to the kitchen and coming back with her cookie jar. "Would you like a cookie? They're chocolate chips, your favorite!"

No response. The only motion he made was a blink as he looked down at his sock covered feet.

Toriel sighed as she placed the jar to the side and crossed her arms. This was going nowhere! There had to be someway to get him out of that angry state. She scratched her chin as she thought of how she could do this.

Unknown to her, the doctor's stomach began to gurgle weirdly. Gaster groaned as he felt pain in that same area. His pupils shrunk as he realized what was going on with him.

"T-Toriel?" he stammered, making her get out of her thought bubble to see his state.

She smirked, noticing that the skeleton was finally speaking to her. "Hello Gaster. Is there anything you need?"

He held onto his stomach as the noises continued to get louder. "C-Could you...show me where the bathroom is again? I-I can't remember."

The queen chuckled. "You're silly sweetie. You're wearing it."

The scientist looked down at his clean white diaper and his face paled (although he's a skeleton and that shouldn't be possible). He looked back up at Toriel, dread taking over his features.

Before he could say anything about it, she interrupted and said. "That's right. You have to go in your diaper."

The skeleton groaned again as he felt his poop coming but he held in it as best as he could. No way was he gonna deal with a dirty diaper. He looked up at the queen with pleading eyes as he asked. "Please Toriel? Take me to a bathroom! I need to go...BADLY!"

She tapped her chin, pretending to think as she answered. "Maybe..." she then smiled giddily. " _If_ you call me Mommy from now on."

He winced as his waste pressed against his behind painfully, wanting to get out of there. The skeleton looked in the loving red eyes of his caretaker and sighed.

What did he have to lose?

Tears started to prick the corners of the scientist's sockets as he asked weakly. "Please...Mommy...?"

Toriel couldn't hide her smile as she hugged Gaster and told him, giggling a little bit. "I told you honey, you're wearing the bathroom."

"But I wanna go to a _real_ bathroom!" he exclaimed. Geez, he was even beginning to sound like a baby.

"But it is a real one."

He whimpered as he continued to squeeze his legs together tight. He grunted as his waste began to push out of him roughly.

This was getting painful. He had to find a way to get out of the living room and get to the bathroom. But how when Toriel was standing guard?

He smiled as he looked at the goat, asking. "Mommy?"

She gushed as she turned to the baby dressed scientist. "Yes sweetheart?"

"Can I have my lunch now? I'm hungry."

The queen smiled politely. "I sure can sweetie! Be right back."

With that, she got up and rushed to the kitchen. As she did this, Gaster decided to make his move.

Quicker than a cat, he crawled off of the playing mat and made his way to the hall. He kept an ear out for Toriel, who - by the sound of it - was looking for that slice of pie.

Perfect.

He crawled down the hallway, opening every single door to find the bathroom. His movement were a bit slower and cautious because every second would've led to his disgusting downfall. But despite this, he pushed forward and sure enough, he found the bathroom, which had been right at the very end of the hall.

He smiled proudly at this accomplishment and was about to go inside when a pair of soft hands lifted him up.

"There you are Gasty! Your lunch is ready~!"

Toriel placed the scientist's head on her shoulder as she headed back in the direction of the living room. And Gaster watched as the restroom became further and further out of reach.

Tears of defeat and anger rolled down his cheekbones. He was so close! He could've made it too. But no, this woman had to take his independence from him and it was not fair!

Before he could yell at Toriel for ruining his chances in using the toilet like an adult, his diaper began to fill up. The skeleton's face grew into a dark shade of purple as the infantile garment he was wearing began to turn brown in color and sag between his legs.

As this happened, the two had reached the kitchen and the goat had placed her baby in his highchair. But she couldn't even leave to get his food from the counter because she not only noticed the tears that came down Gaster's face but the awful odor that filled the room.

Toriel smiled as she picked the skeleton once more. "Aww...it's okay sweetie. All babies have accidents. But don't worry, Mommy's gonna clean you up."

 _All babies have accidents..._ That line came back up in the scientist's head. And it continued to replay itself over and over again until it made no sense.

His mouth wavered just a little bit until all the emotions he was feeling at the moment - hatred, anger, and defeat - building up inside of him and came out in the form of a wail.

"WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!"

 **Gaster: *reads through the chapter before glaring at me* You're an awful person.**

 **I know. And I'm proud to me one ;3c**

 **Chapter 4 will be up soon! See ya around!**

 **~Ty**


	4. Day 3: Giving In with Apologies

**Chapter 4! And yes, it's been a while.**

 **I apologize for the long wait but I had reached a bit of a writer's block for this fic.**

 **But don't worry, I am back…with the intention of finishing it! I hope you like it!**

 **I don't own Gaster or Toriel. They both belong to Toby Fox.**

"Gaster…time to get up."

The skeleton clutched the blankets tightly, refusing to move. Toriel sighed as she looked down at him again.

"Gaster…?"

Still no response.

Ever since the messy diaper incident, the scientist had refused to do anything. After the quick diaper change, he wanted to go to bed. And so he did and stayed in bed for the rest of the day.

And now, the next day, Gaster is refusing to speak to her.

The goat sighed. "I know… that you're mad at me. But…I'm only doing this for your benefit."

The skeleton didn't reply. He shifted in the covers as his body continued to move as if he was sleeping. But in reality, he was simply listening.

Toriel rubbed the back of her neck as she sadly looked at him. She bit her lip as she did her best to hold back her tears. "A-alright…you're free to call me if you need anything."

Nothing.

She stepped out of the room, her hands covering her face as her tears fell. All the while, Gaster simply laid there.

He clutched onto his pillow as he could hear the queen's muffled sobs from the other room. He started to feel guilty.

It was his fault that Toriel had broken down like this. He should've been a bit more open minded about how she would feel. But…what would she know?

She was the one who put him into this mess to begin with. She was the person who had made him wear a diaper and act like a dumb baby. Why should he be worried about her when she was the one who caused all of this?

He cuddled his face into the pillow and took notice of the tears that slid down his cheekbones.

Why…why was he crying?

He was in the right in this whole situation! Why was he feeling so bad?

Maybe…it was the way he was handling this? Uncooperative, angry, worrisome, like the world was against him. But in actuality, someone that really cared about him was right in front of him.

He immediately jumped up from his crib and reached for the bars. He lifted himself up as he stared at the door. He wiped his face again as he shouted.

"Toriel! I'm sorry!"

No response.

He whimpered. "T-Tori…?"

Still nothing.

Gaster's heart sank as his legs began to shake. He collapsed on the bed as he sniffled. His sockets filled with tears as he laid back in bed. He hiccupped as he wiped his face once more.

Before he could lay in a ball of self hatred, the door opened. The skeleton's eyes widened as he turned around and saw the goat of the hour standing right in front of him.

Without thinking, Gaster reached out to her. His hands made grabbing motions as more waterworks went down his face.

He cried. "Mommy! Mommy! I'm sorry! I'm sorry!"

The goat smiled as she reached in and lifted him up. She nuzzled his cheek as he hugged her neck, sobbing into her shoulder. "Oh sweetie, it's alright. I'm sorry too."

Gaster nodded as Toriel began to wipe his tear stained cheeks. She then kissed one of them, causing him to smile a little.

"Let's get you some breakfast."

The skeleton nuzzled into the woman's shoulder in agreement as the two left the nursery.

He had to admit that Toriel was really soft. It felt like he was laying on a pillow. He yawned and then resorting to sucking on his thumb.

The goat noticed this as a smile of satisfaction spread across his mouth. "Where's your binky?"

"Cwib." He answered, thumb still in his mouth.

She giggled. "Alright."

They reached the kitchen without a hitch and the queen had then placed him into his highchair. She then clapped her hands and asked.

"Now, what would like? Oatmeal or applesauce?"

"Oatmeal." He replied simply, his feet kicking lightly against the tray of his chair.

"Already!" she chimed as she started to prep his meal.

As he waited, the scientist continued to kick his feet in his seat. He yawned a little and asked, out of the blue.

"Mommy, I want milk."

Toriel smiled back at him as she went towards the fridge. She grabbed a premade bottle and put it in her hand. She tapped her foot and hummed as her paw lit up into soft flames that grazed the container, heating it up.

After a bit, the goat stopped and then put a drop of it on her palm. She then nodded in satisfaction before giving it to Gaster. "Here you go sweetie~!"

"Thank you Mommy!" he replied, putting the drink into his mouth and sucking on the nipple.

The queen smiled and gently rubbed her baby's head before heading back to prepping breakfast.

The skeleton started to relax until the warmth of his milk.

He sighed in content.

He should've gave into Toriel's loving care ages ago…

 **Also, sorry for the length of this one. I'll try to make the next one longer. See y'all in the next update!**

 **~Ty**


	5. Day 4: Strollers and Flower Beds

**I'm BAAAACK!**

 **You heard me right. I have returned to this story with the intent on hopefully finishing it!**

 **Now I hope you enjoy this!**

 **I do not own these characters.**

"Y'know Gasty sweetie, I've been thinking…"

The skeleton was sitting on the floor, idly moving his blocks around as Toriel sat in her chair while reading a book. As she said this, Gaster turned his head away from his toys and looked up at his caretaker. The goat, meanwhile, had simply placed her snail bookmark on the page she left off on before closing it.

She then looked down at the scientist and continued to speak. "It's been awhile since we've been outside. Asgore had told me to watch his garden while he was gone and…" she smiled sheepishly. "I'm not doing a very good job at being a flower sitter."

Gaster's pupils shrank. "O-Outside?!"

He looked down at himself and his thoughts were immediately filled with fear and dread.

No one needed to see him like this! He would be the laughing stock of the underground! Asgore would probably fire him! His world would crumble into nothing but being a lonely homeless man.

He had a reputation to uphold. It would be ruined if anyone sees him so...childishly dressed.

"Tori...I mean Mommy…" he stated. "With all due respect, I appreciate that you care about the king's marigolds but why can't I just stay here?"

Toriel shook her head. "Oh no no no. You're much too young Gasty. What if you need something and I'm not here to help you? What if you make a mess in your diapee and I'm not here to clean you up?"

The skeleton blushed as the memories of him messing himself filled his mind. He bowed his head, watching as the tips of his sock covered toes touched. He then sighed. "F-fair point…"

"Come on." she went down and picked Gaster up. "Let's get you changed into something more suitable for the outdoors."

~I~I~

Gaster sighed as he stared at his reflection.

He was wearing a plain black T-shirt with denim shorts. On his feet were white socks and hanging from his top was his favorite bunny pacifier.

It took a bit of while for the skeleton to get his clothes on due to all of his fussing and kicking, but Toriel was able to work with it. And after she had finished, she was proud of her work.

And Gaster was still concerned about his image.

"It's alright sweetie." the queen smiled as she lifted the scientist onto her hips. "I think you look absolutely precious~!"

"Well...it could've been worse…" he mumbled, looking down at himself. He then looked back at the goat. "Toriel please, can't we just stay inside?"

She chuckled. "Sweetheart, calm down. We'll only be out for an hour at most. I think you'll live with a bit of fresh air."

"That bit of fresh air is why I want to stay in the here! Why can't you do it tonight when no monsters are out and about?"

She rolled her eyes. "Gaster, it'll be fine." the two of them then walked out of the nursery towards the living room. "Plus, I got you something that might just help you."

He tilted his head, confused as to what she meant. But his question was immediately answered when they entered the living room.

And he hated it.

In the center of the living room was a purple stroller. It was big enough for someone his height, which made him wonder who would be able to make something this big.

Then it hit him.

"Do you like it?" Toriel asked, smiling. "I told your coworkers about what I was doing beforehand and they decided to help me. They were the ones who build your crib, highchair and the stroller. They are so generous…"

"I will never hear the end of it…" the doctor sighed, thinking of multiple ways the other scientists might insult him.

"And look sweetie," she continued, pulling the hood of the stroller up and showing him the bed. "there's a nice spot for you to sleep. Isn't it just wonderful?"

"Yes...super…" he cheered in a bland monotone, clearly not happy.

The goat gave him a warm smile as she placed him in the blankets. The skeleton's eyes widened once his head hit the pillow inside.

He had to admit that the bed was really comfortable. It honestly felt like he was laying on clouds.

He immediately started to relax, making himself comfy within the blankets. Toriel squealed at the adorable smile that crossed Gaster's face.

"I knew you would like it." she smiled, grabbed the scientist's pacifier and putting it in his mouth. "Now you just relax a little. I have to get a few things before we head out."

He wasn't paying attention and simply nodded sleepily. Naptime was approaching. He might as well get a head start.

He yawned and suckled on his binky a little more before quickly falling asleep.

~I~I~

Gaster awoken to the sound of humming. He opened one eye to see the queen watering the flowers. He smiled but it turned when he realized he wasn't in his stroller anymore.

He then looked around and saw that he was laying on the king's throne.

"Oh...hello Gaster. Glad to see you're awake."

The scientist yawned as the goat set the watering can she was using to the side before going over to the skeleton. She then picked him up and took him towards the spot she was working with.

She then dove into the large baby bag that was beside them and pulled out a few toys, which were a small bag of plastic colored blocks and some little trucks.

Tori then said. "Play with those while I tend to the garden."

Gaster pouted but nodded and simply began stacking blocks. His caretaker simply smiling at her child as she continued to work.

Overall, things were relatively calm and quiet. The two stayed to themselves as they either worked or played and no one said a word.

Suddenly, the door to the throne room opened.

"My, I didn't expect visitors...oh hello Toriel."

Gaster's sockets suddenly flew open when he heard the new voice. He shrieked and instinctively his behind Toriel.

"Hello dear." she replied as Asgore came in. "Didn't you have a long meeting to attend to?"

"We finished a bit earlier than anticipated but that's nothing important." He bend down and pointed at the hiding skeleton. "Who's that?"

Gaster felt his heart sink as he looked up at the king. He blushed.

"H-Hello your Majesty…"


	6. Day 5: Asgore the Babysitter

**Did I say that I was gonna update this weekend?**

 **SKYE!**

 **I'm doing it today!**

Gaster knew that today was gonna be different.

He opened his eyes and turned to look up at the ceiling before flipping over. His sockets widened as he saw Asgore standing by the changing table, looking at several different outfits that he had picked out for the skeleton.

The scientist was about to go back to sleep but the king noticed his eyes staring through the bars. Gaster silently cursed to himself as Asgore walked over to the crib and smiled.

"Good morning Doc...I mean, Gaster." he greeted. "How did you sleep?"

He wasn't all that comfortable talking to his employer like this. He felt a bit awkward as well as nervous. He, honestly, rather talked to Toriel. So instead of answering his question, he sat up and suddenly cringed as he felt the wet padding he was currently wearing.

Now he _really_ wanted Toriel…

"Where's Mommy?" he asked, looking at anything but the king's teal eyes. He was searching for her. "I need to ask her something."

"She went out." the goat answered. "We were running out of things so she told me to watch you for a few hours."

Gaster blinked.

No Toriel? But that would mean no more warm bottles. No more lullabies. No more wonderful diaper changes. He would never said this to her directly but he wanted her. And he wanted her now.

She may only be gone for a few hours but it suddenly felt like an eternity to him.

And so, his eyes started to water.

Asgore immediately noticed the sadness that took over the scientist's features. He gasped and covered his mouth with his hands as he thought about what he could do.

Toriel had gave him a long speech about what he was suppose to do with Gaster while she was gone. But he wasn't really listening all that much. It felt like those meetings he had all over again and he didn't want to hear about it. So his objective hearing decided to ignore the other goat and think about what kind of tea he was gonna make with his lunch.

Now, he wished he listened.

He went out of his thoughts as a loud cry filled his ears. He turned and saw the scientist screaming and bawling like an actual baby in his crib. The king frowned as he picked Gaster up and tried to rock him back and forth.

But sadly, that didn't work.

"Mommy!" the skeleton cried. "I want Mommy!"

"I know, I know." he said in a soothing voice, rubbing the smaller monster's back but to no avail. "It's okay. She'll be back in a little while."

"I want Mommy NOW!"

Asgore sighed yet again. "I need to call her."

~I~I~

The sound of her phone ringing made Toriel jump as she was looking through the different markets. She stopped mid-stride and moved to the side for the people that moved right behind her to pass. The queen then dug through her purse and pulled out a flip phone that she quickly answered.

"Hello?"

" _Toriel?"_ Asgore was on the other line. His wife could clearly hear crying in the background.

This made her worried. "Asgore? Is everything alright?"

" _Everything's fine. It's just that...Gaster misses you is all. And also, I cannot seem to calm him down."_

She sighed. "Have you tried rocking him or bouncing him on your hip like I told you to do?"

" _...yes?"_

Toriel sighed once again. "Did you check his diaper?"

" _No. But it is rather wet. There's a yellow stain on it."_

She nodded. "Change him please."

" _But I don't know how."_

"I showed this to you when we were at home! Were you even listening?!"

"Miss? Are you alright?"

Toriel blinked and turned to see a mouse lady working at a vegetable stand. She along with a few people who were buying items from there were staring at her oddly. The goat blushed and smiled sheepishly.

"It...it's fine. I'm just having problems with my husband is all…"

They nodded in understanding as they continued to shop. The queen sighed and put the phone back to her ear. All she heard was silence.

"...hello?"

~I~I~

Asgore successfully changed a diaper.

Now, it took him several tries. There were some tries that failed miserably along with the fact that Gaster was shouting and squirming throughout the majority of the procedure. But nonetheless, the king was able to push through.

He was very happy...but also very tired.

The scientist watched as the king grinned triumphantly at his work. However, he yawned and rubbed his eyes roughly. He lifted Gaster up into his arms and moved him from the changing table to his crib.

"You can't be so sleepy your Majesty…" he stated somewhat blankly. He looked up at the clock and turned back to the goat. "It's only 10 in the morning."

"Yes yes, I know…" he mumbled. "But I've been dealing with meetings and the wife for the past couple of days…" Asgore sighed. "It's stressful…"

Gaster slowly nodded. "I understand." he looked down shamefully. "Sorry about earlier."

"It's fine. I know you're used to Toriel taking care of you and just didn't like the change." he snickered a little. "Literally."

The scientist blushed as the king continued to laugh. He was going to yell at him but simply smiled. The king had a nice laugh and a wonderful smile. He would love to see it a bit more often.

He was shocked when the king picked him back up from his bed and grinned at him. The scientist noticed that through the happiness that was on the king's face, Asgore was very sleep deprived. Bags were visible under his irises and his eyelids was kind of heavy, making it hard for him to stay awake.

Gaster put his fingers through his employer's silky beard, causing both of them to sigh softly in content. The scientist then said.

"Go to bed Daddy."

Asgore blinked. "What?"

"You're tired. You need to sleep."

The king moved the skeleton onto his hip as he rubbed his eyes tiredly. "What…" he yawned. "About you?"

"I'll nap with you."

"But don't you want breakfast? Toriel made you-"

"I don't care about that. I'm not even that hungry anyway." he smiled sincerely. "Rest first. I can eat later."

"Are you sure about that? You don't even want a bottle?"

At the sound of that, Gaster licked his jaw. He was a bit thirsty and a nice warm bottle of milk sounded good to him right now. He nodded with a grin.

"Yes. I would like a bottle."

~I~I~

Toriel came home at around twelve, just before lunch. She hummed a little as she entered the house, hung up her jacket and walked into the living room.

What she saw there made her coo.

On the couch was Asgore and Gaster. They both were wrapped up in one of the bigger monster's blankets. He was holding onto the skeleton as he snored softly, keeping him firmly in his paws to make sure he wasn't going to fall. The scientist had his skull pressed up against Asgore's beating heart, loosely grasping an empty bottle. His mouth was open as well, allowing a bit of milk mixed with drool to slide out.

The queen smiled at the display and went up to them. She then gently kissed Gaster's forehead before giving her husband a light smooch on the lips.

"Good job my love."


	7. Day 6: Everything Stays

**One more chapter left until this story is over. Are you excited? Cause I am!**

 **I hope you enjoy this chapter!**

 **All characters along with the game UNDERTALE itself belong to Toby Fox. Anyone that says otherwise is gonna have a bad time. Although that can't happen because Sans isn't in this story.**

Toriel placed the book she was reading on her lap to look over at Gaster. He was staring up at her for a few stray seconds before looking away. The scientist began fiddling with the dinosaur shirt he was wearing and his cheeks were bright purple.

The goat smiled as she knew what this meant. But to make sure, she asked. "Did someone go potty?"

He continued to stare at the ground but he nodded. Gaster was mostly like this when he needed a change and actually had to ask. The queen loved the shy behavior and found it absolutely precious.

"Come on sweetie. Let's get you cleaned up."

She picked the skeleton off of the floor and headed up the stairs. As they walked, Toriel noticed that Gaster was still playing with his shirt. She raised an eyebrow.

"Is everything alright Gasty?"

"Um…" he sighed as he slowly looked up at his caretaker. "I've been thinking...about...y'know all of this a-and...I kind of like it now."

The queen smiled, kissing her baby on the cheek. "I'm glad." she then looked confused however. "But if that's the case, then why are you so worked up?"

"The other scientists, everyone I know, everyone I love. I don't want things to change because I like this kind of stuff."

"Gaster…"

They had reached the nursery and Toriel strolled over to the changing table. She set the skeleton down and grabbed all the supplies she needed from the shelves below the table. As she got them, she continued talking.

"Nothing gonna change unless you want it to. You could talk to them about it and if you want to accommodate your lifestyle for that then you can. But you could always keep it secret."

The skeleton gave her a deadpan expression. "The other scientists already know." he then started to panic. "They might have already told the rest of the Underground too. My name will be in the books as-"

"Gaster calm down. I told them not to tell anyone. Your secret is safe." she set the supplies to the side and open the padding.

He nodded but Toriel could see by the fidgety nature of the scientist's hands that he wasn't it all that much. His eyes shifted from different areas of the room slowly, the irises never meeting with the queen's

"Look at me Gaster."

He complied. She then lightly pressed her lips on his forehead, causing the skeleton to blush a darker shade of purple.

As she moved the stained diaper to the side and cleaned him up with a few wipes, she spoke. "Everything is going to be fine. You need to relax a little more." she smiled. "And I think I know how."

~I~I~

Gaster sighed in content, his mind slowly easing.

He was laying in Toriel's lap as she sat in her chair. The skeleton had his head resting against the goat's chest as he drank a bottle of nice warm milk.

As he enjoyed this moment of peace and tranquility, he smiled through the bottle's nipple as his caretaker stared down at him. Her eyes, although they were the color of fresh blood, were full of warmth and compassion and she was soft to the touch like a teddy bear.

It made him happy to know that Toriel would be there for him. To have his back when things got tough.

Suddenly, a question came to Gaster's mind. He removed the bottle from his mouth and asked. "Mommy?"

"Yes sweetheart?" she replied, rubbing her hand softly against Gaster's skull.

"Can...Can I stay here? With you and Daddy?"

The goat's eyes widened at the question. She honestly didn't expect him to ask that. Toriel then thought about it for a second before asking another question.

"But...don't you want to go back to your work? To actually have some freedom to be an adult?"

"No." he answered simply, nuzzling closer to the goat. "I wanna stay here with you and Daddy."

Toriel couldn't be any happier. She smiled brightly and kissed the skeleton on the cheek, causing him to giggle. She beamed once more. "Then of course you can stay."

Gaster cheered and hugged the boss monster. "Thanks Mama!"

"You're welcome."

~I~I~

"Daddy! Daddy!"

Asgore chuckled as Gaster kicked his feet against the tray of his high chair. The king walked over to the scientist and set the baby blue bowl he was carrying in from of him.

"Yes Gaster? What is it?" he asked with a smile, already knowing what it is since the skeleton told him several times already.

"I'm staying with you and Mommy!" he cheered as Asgore got a spoonful of applesauce and fed it to him.

"Really now?"

"Uh huh! Mommy said so!"

The king nodded. "I know."

"And…" he ate the food and finished chewing before saying. "I'm super happy!"

Asgore nodded. "I see."

Gaster giggled.

~I~I~

Toriel looked away from the book she was reading to realize that the living room was awfully quiet. The only sound she heard was from Asgore washing the dishes. She looked on the playing mat and smiled as she saw Gaster's sleeping frame.

She set her novel aside to pick the skeleton up. As she did this, she noticed the pile of papers that were placed around him and picked one of them up.

Toriel nearly cried.

On the paper was a picture of himself along with Toriel and Asgore holding hands. They were surrounded by a big heart and on the bottom it read:

 _ **I love my Mommy and Daddy!**_

She looked at the skeleton and kissed his forehead. "We love you too."

 **I'll try to post the last chapter next week!**


	8. Day 7: Welcome Home

**The final chapter of Gaster's Visit! I hope you all like it!**

 **I own NONE of the characters!**

Gaster awoken with a smile.

He sat up and stretched a little before looking around the room. His smile grew when he saw Toriel bringing a basket of laundry into the room. He could practically smell the sweet, flower scented detergent from his crib, telling him that they were cleaned recently.

The queen noticed the skeleton and waved, setting the basket aside and walking over to the bed. "Good morning sweetie!"

"Hi Mommy!" he piped, reaching up to her. "Uppy pwease!"

Toriel gladly obliged by grabbing the skeleton and bouncing him on her hip. She gave him a little kiss on the forehead before walking with him into the living room. In there, Asgore was reading his newspaper with a cup of tea beside him.

He looked away from his reading and greeted the two. "Good morning."

"Hi Daddy!" Gaster waved before reaching out to the larger goat. "Can I read with you?"

"Sure thing."

Toriel chuckled as the king grabbed the scientist and placed him on his lap so that he could read the paper as well. She smiled at the two and then asked. "Don't you want breakfast Gasty?"

"Baba." he answered simply. Turning to her, he added. "Can I have milk in it?"

She nodded and headed into the kitchen.

Honestly Gaster wasn't really there to read with the king. None of the stories in there was really all that interesting. He just wanted to get comfy in his daddy's lap. Feel his warm and soft beard. Hear his soothing heartbeat.

It made him feel good.

"Here you go~!" Toriel chimed sweetly as she came back from the kitchen with a warm bottle of milk.

The skeleton took it and smiled in thanks before slipping the nipple into his mouth and sucking on it while watching Asgore read.

 **~I~I~**

"Mommy..."

The goat was in the midst of washing the dishes from the breakfast that she and her husband ate earlier to turn to Gaster. She smiled down at him. "Yes sweetheart?"

"I um..." he began to fiddle with the sleeve of his purple footies. "I..."

She nodded as she grabbed the skeleton and noticed the area between his legs were really wet. "My my my. Looks like someone leaked through their diaper."

Gaster blushed heavily as he looked down at his feet shamefully. "I'm sorry..."

"It's fine. I can get you changed."

She then started to leave the kitchen, humming a little tune as she went.

 **~I~I~**

Gaster laughed as Asgore laid on the floor, throwing him into the air like a ball. As the king continued this, the skeleton laughter intensified.

He was having so much fun with this.

"My, you are such a giggly monster aren't you?" Asgore cooed, stopping his tossing to nuzzle him. "So giggly~!"

Gaster continued to laugh as the tossing resumed. "Higher Daddy! Higher!"

"Oh you want to go higher eh? Here. We. Go!"

The skeleton whooped as he went a few inches higher. He squealed and giggled as his daddy continued with this until suddenly, he was caught. Gaster blinked as he looked over and saw Toriel holding him.

She was glaring down at her husband as he smiled sheepishly back at her. "Howdy...?"

"Give me one good reason not to hurt you right now." she stated, clutching her baby close like a valuable possession.

"Because you love me...?"

She sighed, setting Gaster on the floor. "That is very true but don't do that again. He's very fragile and precious. I don't want anything to happen to him. Is that understood?"

"Yes ma'am." he replied.

Toriel then turned to the skeleton. "And as for you sweetie, don't get into games that could get you hurt. Alright?"

"Okay Mommy." he nodded. "Won't happen again."

"Thank you." she bend down to kiss both of them on the cheek. "Behave yourselves!"

 **~I~I~**

"WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!"

Toriel and Asgore jumped at the sound of the skeleton crying. They looked at the floor to see Gaster bawling his eyes out. Immediately after that, a horrible scent reached their noses

They looked at one another and then turned back to the bawling skeleton.

"Not it!" the king exclaimed, raising his hand.

His wife crossed her arms. "No. You're doing it. I changed him this morning."

He slowly put his hands down and sighed. "Oh alright..."

"If it makes you feel any better, I'll be here to help you out."

He nodded and she left out of the room to get the supplies. As Toriel went to go get it all, Asgore grabbed the skeleton and held him in his arms. His nose wrinkled in disgust as he put the diaper mat out from the closet.

Using one hand, he rolled it out and laid Gaster on it. The skeleton slipped his thumb in his mouth to soothe himself from this uncomfortable experience. The king moved the scientist's digit from his mouth and replaced it with his pacifier.

"I'm back." Toriel chimed as she brought all the things they needed.

Asgore nodded, getting on his knees as he gently took off the scientist's diaper. His nose immediately filled up with the awful stench and he gagged. Quickly, he wrapped the poop filled diaper into a ball and used some baby wipes to clean up the mess that was left over. Toriel grabbed all of the dirty items and rushed to the trash can.

He then opened the new diaper and placed it under his bottom and between his legs. The king then grabbed the baby powder and sprinkled it all on the cleaner garment.

"Make sure you rub it in." Toriel suggested. "So all the powder spreads evenly."

Asgore nodded, rubbing the powder into both the diaper and his body. Afterwards, he pulled it up and taped the tabs. He beamed. "I'm done!"

""Almost." she chuckled, pulling down the purple T-shirt the skeleton was wearing and lifted Gaster up on her lap. "And now you're done." she gave him a high-five. "Great work dear!"

~I~I~

Toriel blinked as he heard a bit of snoring. She along with Asgore and Gaster were sharing a blanket and watching a movie. As the movie went out the trio were starting to get a bit sleepy.

She was about to drift off until she heard the snoring. She turned and smiled as she saw Gaster up against her arm, drolling just a bit as he slept. She gently placed his pacifier into his mouth before picking him up and was about to leave the room with him before turning to see Asgore dozing off as well.

"Good night my love." she said, kissing him on the lips before walking upstairs.

She reached the nursery without any trouble and gently placed the skeleton in his crib. The queen then covered him up with a blanket and kissed his forehead.

"Good night Gasty." she smiled down at him as she left the room. "And welcome home."

 **The end! Another story COMPLETED!**

 **See you guys in the next update!**

 **Bye~!**


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